• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.37 no.6
• /
• pp.417-426
• /
• 2019

Conventional visualization of PM (Particulate Matter)10 flows applies superimposition of concentration distribution maps and wind field maps. This method is efficient for small scale maps where only macro flow trends are of interest. However, in the case of urban areas, local flows are difficult to model at micro level using wind fields, and therefore different methods of flow extraction is deemed necessary. In this study, flow information is extracted and visualized directly from the PM10 density data by using the gravity model. This method has the advantage that additional information such as wind field is not necessary for estimating the intensity and direction of PM10 flow. The extracted spatio-temporal flow patterns of PM10 are analyzed with relation to traffic information.

• Analytical Science and Technology
• /
• v.24 no.4
• /
• pp.249-255
• /
• 2011

Swelling of starch granules by water-sorption causes a progressive or sometimes abrupt change in sorption behavior as a result of structural alterations and the possible exposure of new sites with high affinity for water. It is thus of interest to examine the time-dependent change in the size or shape of the starch granules. Gravitational field-flow fractionation (GrFFF) utilizes the earth's gravity as the external field, and is useful for separation of micron-sized particles with larger particles eluting earlier than smaller ones. In this study, GrFFF was used to monitor the swelling of two starch granules, potato starch and sweet potato starch during contact time of 11-12 days at room temperature in water. Results from GrFFF were compared with those obtained from optical microscope (OM). For both starch granules, the mean sizes were increased with time spent in water.

• Journal of the Korean earth science society
• /
• v.30 no.6
• /
• pp.692-698
• /
• 2009

Wavelet transform has been widely used in terms that it may overcome the shortcoming of conventional Fourier transform. Fourier transform has its difficulty to explain how the transformed domain, frequency, is related with time. Traditional semblance technique in Fourier transform was devised to compare two time series on the basis of their phase as a function of frequency. But this method is known not to work well for the non-stationary signal. In this study, we present two applications of the wavelet-based semblance method to geophysical data. Firstly, we show filtered geomagnetic signal remained with components of high correlation to each observatory. Secondly, highly correlated residual signal of gravity and magnetic survey data, which are also filtered by this semblance method, is present.

• Journal of Astronomy and Space Sciences
• /
• v.6 no.1
• /
• pp.29-39
• /
• 1989

The instability of the infinite disk system with the effect of the surrounding magnetic field has been investigated and the initial mass function has been obtained. We present the fact that the infinite system becomes unstable by the long wavelength perturbation if the magnetic pressure is greater than the gas pressure, on the other hand, it also becomes unstable by the short wavelength perturbation if the gas pressure is greater than the magnetic pressure.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.12 no.3
• /
• pp.353-362
• /
• 1999

This study is aimed to obtain the critical crack lengthes of the concrete gravity dam and to investigate variation of the effective stress intensity factors at the crack tips of multiple cracks. Applied loads are dynamic load composed of blast vibration and hydrodynamic pressure which can be considered in case of the blast work at near construction site, in addition to static load composed of hydrostatic pressure, crack pressure, and gravity load of the dam. The critical crack lengthes were calculated according to the crack locations, directions, and magnitudes of blast vibration. Also variation of the effective stress intensity factors with respect to the multiple crack shapes and distances between the crack tips was investigated.

• Journal of Energy Engineering
• /
• v.12 no.1
• /
• pp.17-22
• /
• 2003

The present study was conducted to obtain the fundamental knowledge on the manufacturing and operating characteristics of a small scale CPL (Capillary Pumped Loop) heat pipe. CPL heat pipes are able to transfer heat effectively at any orientation in a gravitational field over long distances. An experimental model with an evaporator of a circular plate shape was designed and manufactured and its operating performances were tested. A Bronze powder sintered metal plate of 3 mm thick and $\Psi$ 50 mm was used as wick and ethanol was used as working fluid. An experimental apparatus was set up to ascertain the operating conditions oi CPL at different heat load and an surrounding temperature at the condenser was maintained about 13$^{\circ}C$.

• Journal of the Korea Computer Industry Society
• /
• v.6 no.2
• /
• pp.331-336
• /
• 2005

The closed movement produced vertically on the position of a motor is a notation movement produced by a notation force , while the horizontal movement can be shown by the coriolis force and the transverse force of realizing that the closed movement of the closed system is to be rotation motion. The notation movement is a vertical closed movement and by searching the equation which becomes an equation model, after comparing the simulation data from the equation model with data of a real device to use it into the computer simulation model, the additional variable elements were decided. As the result, the energy imbalance element is added as a variable about load which is relevant to friction coefficient and pole of a motor in the gravitational field. The simulation can be applied as a real physical law of the graphic game and haptic program.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.8
• /
• pp.87-93
• /
• 2002

In general, station relocation for a geostationary orbit satellite is formulated as a request for moving the spacecraft from its present longitude to the target longitude within a given time interval. The station relocation maneuver is composed of drift orbit insertion maneuver and target orbit insertion maneuver. During station relocation, the satellite orbit is continually influenced by the non-spherical geo-potential. When we plan a maneuver, if we do not consider the influence, the satellite may not be relocate to desired longitude successfully. To solve this problem, we applied the linearised orbit transfer equation to acquire maneuver time and delta-V. Nonlinear simulation for the station relocation of multiple satellites is performed in order to verify the distance between two satellites.

• Journal of Astronomy and Space Sciences
• /
• v.10 no.2
• /
• pp.163-188
• /
• 1993

On the framework of Tolman spacetime model, the caustics around a local perturbed region in redshift is due to the local expansion rate induced by a local density inhomogeneity in real space. We have compared the caustics in redshift space, which are analytically obtained, with the observed redshift-distance patterns of galaxies which are belonging to Coma and Perseus clusters. For the Abell density distribution model and polytropic density profiles which are well-fitting the optical and X-ray observations, respectively, the size of caustics which is defined by "turnaround radius" of a local density perturbed region should give constraints on the sizes and masses of rich clusters and give also a clue to understand the state of hot X-ray emitting gas.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.85-89
• /
• 2003

In a closed square cavity filled with a liquid, a cooled the upper horizontal wall and a heated the lower horizontal wall, the flow isn't generated under the ground-based condition when Rayleigh number is lower than 1700. In such case the flow phenomena near an air bubble under a cooled horizontal wall were investigated. The temperature and the flow fields were studied by using the Thermo-sensitive Liquid-Crystal and the image processing. The qualitative analysis for the temperature and the flow fields were carried out by applying the image processing technique to the original data. Injecting bubble at the center point of upper cooled wall, the symmetry shape of two vortexes near an air bubble was observed. The bubble size increased, the size of velocity and the magnitude of velocity increased. In spite of elapsed time, a pair of two vortexes was the unique and steady-state flow in a square cavity and wasn't induce to the other flow in the surround region.